About a shoulder MR arthrogram
The shoulder is a ball-and-socket joint with a very shallow socket. A rim of cartilage called the labrum runs around the socket, deepening it and helping hold the ball in place, and the biceps tendon attaches to the top of it. Because the shoulder relies on these soft tissues for stability, injuries to them can cause pain, clicking or catching, weakness and a feeling that the shoulder is loose or may come out of joint.
Shoulder dislocations most often happen forwards (anterior dislocation), and can tear the front of the labrum. This is known as a Bankart lesion, and it can leave the shoulder unstable and prone to dislocating again. Tears at the top of the labrum where the biceps attaches are called SLAP tears; they can follow a fall on an outstretched arm or repeated overhead activity, such as throwing.
In an MR arthrogram, contrast dye is injected into the shoulder joint before the MRI. The dye fills the joint and outlines the labrum, capsule and cartilage, showing tears that may not be visible on a standard MRI. MR arthrography is particularly useful for the shoulder after a dislocation and is usually requested by an orthopaedic surgeon or sports medicine specialist to help plan treatment. Left and right shoulders are separate scans.
What happens during the scan
An MR arthrogram is done in two parts. First, a small amount of contrast dye (gadolinium) is injected directly into the shoulder joint. The skin is cleaned and numbed with local anaesthetic, and the needle is guided into the joint using X-ray (fluoroscopy) or ultrasound. You may feel a sharp scratch, some pressure and a feeling of fullness in the joint, but it should not be painful. You will then be asked to move the joint gently to spread the dye.
Shortly afterwards you have the MRI scan. You lie still on the scanner bed with the shoulder in a coil while the pictures are taken; the scan itself usually takes about 20–40 minutes. The scanner is loud, so you will wear ear plugs or headphones, and the radiographer can talk to you throughout. Allow up to 1½ hours for the whole appointment.
Referral needed: this scan requires a referral from a specialist, such as an orthopaedic surgeon, sports medicine doctor or specialist physiotherapist. You can upload the referral when you book.
What the scan can show
A shoulder MR arthrogram can help to look at:
- tears of the labrum, including Bankart lesions after dislocation and SLAP tears at the top of the socket
- damage to the ball of the shoulder from a dislocation
- stretching or tearing of the joint capsule and ligaments
- rotator cuff tears, including small partial tears on the underside of the tendons
- damage to the joint cartilage
- the shoulder after stabilisation surgery
Preparing for your scan
No special preparation is usually needed, and you can eat and drink normally. Because the injection goes into a joint, tell us when booking if you take blood-thinning medicines, have a skin infection near the joint, have kidney problems or have had a reaction to contrast dye. Arrange for someone else to drive you home, as you should not drive for 24 hours afterwards.
You can usually eat, drink and take your normal medicines unless the scanning centre tells you otherwise. Wear loose, comfortable clothing without metal zips or buttons, and leave jewellery at home. You will be asked to remove metal items such as hair clips, hearing aids, coins and keys, and you may be asked to change into a gown.
Before the scan you will complete a safety questionnaire. Tell the team if you have a pacemaker, any metal implant, surgical clips or other device, if you have kidney problems or allergies, or if you are, or might be, pregnant or breastfeeding. If you feel anxious in enclosed spaces, let us know when you book. Some centres can offer a relaxant, and if you take one you will need someone to take you home and must not drive for 24 hours.
After the arthrogram
The joint may feel stiff, swollen or full, and you may hear it creak or gurgle as you move it. This usually settles within 48 hours. Keep the joint moving gently, but avoid vigorous exercise for at least 24 hours. An ice pack and a simple painkiller can help. Do not drive for 24 hours after the injection. Contact your GP or NHS 111 if the joint becomes increasingly painful, red, hot or swollen, or if you develop a fever, as infection, although rare, needs prompt treatment.
Frequently asked questions
Do I need a referral for an MR arthrogram of the shoulder?
Yes. This scan requires a referral from a specialist. Please upload your referral when you book so the scanning centre can check that an arthrogram is the right test for you.
What is the difference between an MRI and an MR arthrogram?
A standard MRI is taken without anything being injected into the joint. In an MR arthrogram, contrast dye is injected into the joint first. The dye fills the joint and outlines the cartilage, ligaments and other structures, which can show small tears that a standard MRI may not.
Is the injection painful?
The skin is numbed with local anaesthetic first, so most people feel only a sharp scratch and some pressure. The joint may feel full or stiff for a day or two afterwards.
Can I drive home afterwards?
No. You should not drive for 24 hours after the injection, so please arrange for someone to take you home.
Why is an arthrogram used after a shoulder dislocation?
A dislocation can tear the labrum and stretch the joint capsule, which can make the shoulder likely to dislocate again. The contrast dye outlines these structures clearly, helping your specialist decide whether you need physiotherapy or surgery to stabilise the shoulder.
Sources
- RadiologyInfo.org – Arthrography
- United Lincolnshire Hospitals NHS – MRI Arthrogram
- South African Journal of Radiology – Imaging of SLAP lesions
- Radiology Assistant – Shoulder instability (MRI)
- NHS – MRI scan
The information on this page has been gathered from various sources and is provided for general information only. It is not medical advice. TOP MRI is not liable for the accuracy or completeness of this information. Please speak to your doctor or the scanning centre about your own situation.